/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.parse;

import java.sql.SQLException;
import java.util.List;
import org.apache.phoenix.compile.ColumnResolver;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.function.DistinctCountAggregateFunction;
import org.apache.phoenix.expression.function.FunctionExpression;

/**
 * @since 1.2.1
 */
public class DistinctCountParseNode extends DelegateConstantToCountParseNode {

  public DistinctCountParseNode(String name, List<ParseNode> children, BuiltInFunctionInfo info) {
    super(name, children, info);
  }

  @Override
  public FunctionExpression create(List<Expression> children, StatementContext context)
    throws SQLException {
    return new DistinctCountAggregateFunction(children, getDelegateFunction(children, context));
  }

  @Override
  public void toSQL(ColumnResolver resolver, StringBuilder buf) {
    buf.append(' ');
    buf.append("COUNT(DISTINCT ");
    List<ParseNode> children = getChildren();
    if (!children.isEmpty()) {
      for (ParseNode child : children) {
        child.toSQL(resolver, buf);
        buf.append(',');
      }
      buf.setLength(buf.length() - 1);
    }
    buf.append(')');
  }
}
